AAS 95-366

An Analysis of the TOPEX/Poseidon Operational Orbit: Observed Variations and Why

R. B. Frauenholz, R. S. Bhat and B. E. Shapiro, Jet Propulsion Laboratory, Pasadena, CA, R. K. Leavitt, Sterling Software, Inc., Pasadena, CA

Abstract

Following launch on 10 August 1992, TOPEX/Poseidon began and continues a very successful global study of the earth's ocean circulation using a combination of dual-frequency radar altimetry and precision orbit determination. A joint mission of NASA and the French Space Agency CNES (Centre National d'Etudes Spatiales), TOPEX/Poseidon has completed its three-year primary mission and has begun a three-year extended mission phase. Precision orbit determination (POD) performed by the Goddard Space Flight Center (GSFC) using laser ranging and DORIS tracking data (CNES) defines radial position relative to the geocenter to an unprecedented accuracy of ~5 cm RMS.1 The POD results are utilized to accurately reconstruct the operational orbit history in terms of precise classical mean elements. This paper explains observed variations in the mean orbital elements and their effect on the satellite's 10-day repeat ground track, which has been successfully maintained within the stringent #1-km control limits in equatorial crossings.